1. Field of the Invention
This invention relates to framing projectors and more particularly relates to a Ceramic Metal Halide (“CMH”) retrofit kit for an incandescent framing projector.
2. Description of the Related Art
A framing projector is a precision light fixture that directs light onto an object without spilling light onto unwanted areas beyond the object. For example, a framing projector may be used to precisely project light onto a painting without projecting light onto the painting's matting and frame. A framing projector may be used to highlight paintings, photographs, sculptures, etc. Framing projectors may be used indoors or outdoors. Outdoor framing projectors may be used to project light onto certain portions of a building or onto a sculpture.
Traditionally, framing projectors have used incandescent lamps as a light source. Outdoor fixtures have more recently used high intensity discharge (“HID”) lamps such as metal halide (“MH”) and high pressure sodium (“HPS”). However, until recently HID lamps have been inappropriate for indoor use. Traditional HPS and MH lamps are relatively large and require a long startup period before stabilizing at a uniform brightness and color. HPS lamps produce a yellow light with a low color rendering index (“CRI”) that is typically inappropriate for use with artwork and is typically only used to highlight building structures of certain warm colors. MH lamps traditionally also have a low CRI and are subject to color shifting over time.
Indoor framing projectors frequently use incandescent lamps of some type. Typically quartz and halogen lamps are used in various forms. Many framing projectors use a lamp with a bulb in a T4 configuration. Incandescent lamps are typically used in indoor framing projectors. Incandescent lamps have a benefit of instantaneously providing light when powered and providing a fairly stable image and color. However, incandescent lamps typically have a short lamp life and produce tremendous heat at high wattage. A short lamp life requires constant attention by maintenance personnel to replace lamps. Heat must be dissipated by a light fixture without causing a fire. Infrared heat emitted from an incandescent lamp can also be a problem because of its effect on art work and framing projector attachments. For example, emitted infrared light may require a filter.
Incandescent lamps, such as a quartz lamp in a T4 configuration, also typically have a long filament that affects focusing. A point source of light is an ideal source because a parabolic reflector can be shaped with a focal point positioned with respect to the point source. The focal point of the reflector is typically positioned beyond the lamp, other wise the lamp would block or shadow the reflected light. Incandescent lamps with a long filament used with a parabolic reflector cannot be focused as crisply as other lamps that are more like a point source and may produce an undersized projected image. A long filament may also sag as it is heated which may affect focusing and lamp life.
Halogen lamps in an MR16 or similar configuration may also be used in a framing projector. MR16 halogen lamps have a longer lamp life, but are limited because they have an integral reflector. An integral reflector reduces design flexibility by limiting how light is reflected through framing projector lenses. MR16 lamps also produce a lot of heat, but not as much as a quartz lamp.
A sectional view of a framing projector with an incandescent lamp is depicted in FIG. 1. FIG. 1 includes a framing projector 100 with a framing projector body 102 that includes an incandescent lamp 104 in a quartz T4 configuration with a long filament 106. The quartz lamp 104 fits in a socket 108 that is part of an incandescent lamp base 110. The incandescent lamp base 110 is attached to the framing projector body 102 using fasteners 112, such as spring loaded bolts, screws, etc. The fasteners 112 are typically arranged in a specific pattern to allow the incandescent lamp base 110 to mate to the framing projector body 102.
The framing projector body 102 typically includes a parabolic reflector 114 configured with a focal point beyond the center of the filament 106 of the incandescent lamp 104. The center of the incandescent lamp 104, which is positioned with respect to the focal point of the parabolic reflector 114, is depicted in the framing projector 100 as the intersection of a horizontal axis 116 and a vertical axis 118. As depicted, a large portion of the filament 106 of the incandescent lamp 104 is above and below the horizontal axis 116, which decreases the ability to focus projected light. The framing projector body 102 typically includes lenses 120 that condense and focus light. The framing projector body 102 also includes a front cone assembly 122 and a focal tube assembly 125 that extends out of a framing projector housing and directs projected light through an objective lens 123 which determines the overall size of the light beam emitted to cover the intended target.
Framing projectors 100 with incandescent lamps 104 typically include a metal conduit 124 connected to the incandescent lamp base 110 that houses wiring (not shown) connected to the incandescent lamp socket 108. The metal conduit 124 is typically required due to the large amount of heat produced by the incandescent lamp 104. Non-metallic covering for wiring typically cannot be used with framing projectors 100 with incandescent lamps 104 because the framing projector body 102 and incandescent lamp base 110 reach temperatures exceeding temperature ratings of non-metallic wire coverings. The metal conduit 124 typically includes an elbow connector 126 and flexible metallic conduit 128. The elbow connector 126 is a hindrance because it limits available positioning of the framing projector 100 within a framing projector housing.
Indoor framing projectors 100 with incandescent lamps 104 have been around for many years so thousands of existing framing projectors 100 with incandescent lamps 104 are installed and functioning. New framing projectors 100 with incandescent lamps 104 are currently being sold and installed. Installation of a framing projector 100 with an incandescent lamp 104 is problematic because of the high amount of heat and energy produced by the incandescent lamp 104. Framing projector housings that have framing projectors 100 with incandescent lamps 104 typically require ventilation holes. Ventilation holes in framing projector housings prevent achieving an insulation contact (“IC”) rating or an airtight rating.
A light fixture with an IC rating is beneficial because insulation can be placed against and over the light fixture. As many as 33 states currently require a recessed light fixture to have an airtight rating. A light fixture with an airtight rating is energy efficient because conditioned air cannot escape in any significant amount through the light fixture.